Apparatus for measuring muscle strength



June l5, 1954 l.. B. NEWMAN 2,680,967

APPARATUS FOR MEASURING MUSCLE STRENGTH Filed Sept. 4, 1948 j? JiIII'I'II' ||||||||I Patented June 15, 1954 UNITED STATES PATENT gaat?YOFFICE APPARATUS FOR MEASURING MUSCLE STRENGTH 2 Claims.

This invention relates to an apparatus for measuring muscle strength.

In the treatment of conditions involving impairment of muscles, such asmuscles of the legs, arms, lingers, etc., it is frequently desirable toknow the rate of increase in muscle strength over periods of time.Usually the physician relies upon his memory of the patients muscularstrength in the alicted muscle during the past treatment or treatmentsand tries to judge whether or not the muscles are being strengthened,and the extent thereof.

It is one of the objects of the present invention to provide a device ofa simple construction which a physician or therapist may use to causethe patient to push or pull against and which de vice will measure themaximum force that the patient can exert. urements will serve as arecord of the change in muscular strength of the muscles involved.

In accordance with the principles of the present invention there isprovided a simple device which the physician can hold in the palm of hishand and by pushing against the device cause the device to push againstthe patients nger, arm or leg involving the aiiiicted muscle. Uponinstructions, the patient resists the physicians push as long as he can.When the limit of the patients resistance is reached the aiiiicted limbdrops back and at the same time the physician has a record on theinstrument which is a measure of the amount of force that was required tforce the afflicted muscle back,

In order to use the same device to measure the strength of muscles thatmay vary greatly in power and in order to secure accurate readings, thedevice may be provided to receive springs of varying tension which canbe added to the device, or substituted one for another, so that underone condition the numerical calibration of the scale of the gauge may bein terms of one unit, such as pounds, and under another condition it maybe in terms of a smaller unit, such as ounces, or other fractional partsof a pound.

The physician in testing the patients muscle or group oi muscles canpush the device against the extremity that is being or should beactivated by the afliicted muscle and have the patient resist thephysicians thrust until the physicians thrust overcomes the resistanceAof the patient. The maximum reading on the gauge is the maximumresistance offered to the. physician by the patients thrust and is afunction of the muscles strength. It is also possible to use the deviceof the present invention in a somewhat different Recorded data of thesemeasmanner to accomplish the same result. For instance, the resistancemeasuring device or gauge may be fixed in a frame or bracket and thepatient then exerts a muscular force against the member that isconnected with the device.

In accordance with the principles of the present invention the musclestrength measuring device can also be used in connection With the pullmethod for determining the pulling strength of a muscle or group ofmuscles. A cuff is placed on the limb or other part of the body that ismoved by the muscle involved and the patient transmits his muscular pullto the device through the cuff. Either the push or pull method ofdetermining muscular strength can be used in connection with the deviceof the present invention to measure the strength of a single muscle orgroup of muscles that controls the movement of any external part of thebody, including the head, the neck, the torso, the arms, the legs, thengers, etc.

One of the advantages of the present invention is that it enables thephysician to measure the patients muscular strength before treatment isinstituted so that the physician is able to evaluate the benefits of thetreatment for the purposes involved.

A further object of the present invention is to provide a device of theabove mentioned character which is simple and economical of constructionand reliable in its action. It is a still further object of the presentinvention to provide a device of the above mentioned character whereinthe readings of the maximum force of the muscle or group of musclesinvolved may be made directly or at a remote point.

The attainment of the above and further objects of the present inventionWill be apparent from the following specication taken in conjunctionwith the accompanying drawing forming a part thereof.

In the drawing:

Figure 1 is a longitudinal sectional View through a device embodying thepresent invention;

Figure 2 is a right hand View of the device of Figure 1;

Fig. 3 is a longitudinal sectional View illustrating a modifiedconstruction; and

Figure i is a longitudinal sectional view through still anotherembodiment of the present invention, the gauge at the end thereof beingshown in elevation.

Reference may now be had more particularly to the drawing wherein likereference numerals designate like parts throughout.

The measuring device of Figure 1, indicated in general by the referencenumeral l, comprises a metal cylinder 2 of a size such that it canconveniently be grasped by the hand. The cylinder is closed at one endby a circular plate 3 that has an expansible metal bellows 5, welded orotherwise secured to the inner surface of the plate 3 as, for instance,by a line of weld 6 that extends around the entire periphery rof 'thebellows and makes an 'air-tight, liquid-tight seal with the plate 3. Theplate 3 in turn is welded to the cylinder 2 as by a line of weld 1 thatextends around the entire circumference of the plate 3 and provides aliquid-tight seal between the plate and the cylinder 2. A rod 9 isslidable through the plate 3 making a suciently 'loose 't therewith topermit the free Iflow-of air from one side to the other side of theplate 3. The end iii of the rod is screw threaded to 'the bellows at thecenter thereof, and the opposite end of the rod il has'a pressure knobli threaded thereon. A circular` yclosure plate i5 is welded to theinside of the cylinder 2 to make a liquidtight seal therewith, .theplate having a flange i5 for vfacilitating' this action. The space onthe inside ci' the cylinder 2 between the bellows 5 and the plate iti-islled with a liquid, generally anoil, suchasfis vused in expansionbellows.

A standard :fluidpressurefgauge is mounted in the end of the cylinder 2opposite the closure plateV 3. The .gauge includes the usual glassclosure "2l, a pressure actuated indicating pointer 22, and a calibratedscale 23. n addition the gauge'includes the usual follower vpointer 2Qthat is actuated by the .pointer 22 as the pointer 22 moves vfrom zerotowards the opposite end of the scale, vsaid follower 2li remaining inthe furthest position `in which it was 4pushed by the pointer 22even-'after the;pointer 22 -recedes from its maximum position. Thefollower ...pointer 2d is returned to its initial position by .fa sknob23 that extends through `the glass plate 2l and is secured'tothefollower :pointer 2li. The Bourdon tube of the pressure .gauge 2E isconnected to the pressure chamber VE by a'connection 25 that threadsvonto a nipple S `formed at the center of the circular closure plate l5so that the .Spressure within the :pressure chamber il is communicatedto`the :gaugef to=actuate the .pointer 22 thereof.

The structure thus far describedis very compact. The physician -lgrips.the measuring device i by embracing the cylindrical casing 2 with onehand. lf the physician is to use this device `to measure the strengthpfthe muscles controlling a finger-'of 'a patient, the physician, holdingthe cylinder 2 vinone hand, .presses the knob El yagainst the fingerofthe .patient and asks the :patient"to'resistithe `push of theknob lasthe physician vpushes 'the device l Vmore and more firmly against thefinger of the ,'patient. fAs long as the patient is resisting theapressurefof the knob H there is -a consequent rise of -pressure offluid inthe chamber i1 and this rise of Apressure is lmeasured. by thepressurefgauge 2), the pointer 22 moving across the scale 23. -When the:patient can no `longer resist 'the pressure his finger drops and the,pressure `within the pressurechamber H immediately drops to-zero. 1nthe meantime the pointer 22 'has moved the follower .pointer 24 :to aposition indicating the maximum pressure that was attained.Theiphysi'cian can vthen `in avery simple manner read the Ymaximumpressure which 'is determined by the position of theffollowerapointer24.Theressaid bellows having a neck 31 that extends through the back of thecasing and on which isimounted a pressure gauge 2G which is identical inconstruction with that ofthe pressure gauge previously described. Acoupling nut 25 couples the gauge 2twith the neck 3l of the bellows forcommunicating the pressure within the bellowsto the pressure gauge 2t. Acircular cover plate :it closes the opposite end of the casing beingL.secured theretoifin any :desired manner as, for instance, by a seriesof l countersunk :screws 4i 'that thread into Aaperipheral flange 42 'ofl'the cup-shaped casing. Flherod19-, that corresponds with the rod 'S ofv'Figure l, is 4secured -at one end to the `bellows 35. At the other endthe rod -has the 'knob V4H threaded thereon. -A calibrated=compressionspring 'is provided between the lknob 'ii and the'covergplated.

rflfhe device'of Figure 3 :is 'used in exactly Vthe same manneras is theAdeviceofiiigure l. The spring l5 performs "thefdefinite function ofpermitting :changing of the "scale readings yas may be required 'whenvdealing with Amuscles yof `.different strengths. For f-instance, withthe spring 45 in position the device fm'ay be used to measure muscularstrength fofcomparatively strong muscles, the gauge being calibrated sothat lthe numbers on =the'dialof the gauge indicate, for instance,.ip'oun'ds of p'ressur'e. -Tf it is 'desired to use the same A'device`for testing a comparativeiy weak'muscle, where'thetdtalipressureexerted'by the patient lm'ay be `on'lyonepound or a traction tof Tapound, 'the Ispring 45 may fbe removed, y'in 'which case sa small:pressure on the knob Il will iproduce -as :large a movement of thepressure gauge pointer @as would have Abeen produced byfa largei'pressure had the spring @5 been in place The `spring'is acalibratedspring so tha't with the 'spring lin place lthe readings on 'the rdialdesignate pounds .of pressure and with 'the ,spring `removed thereadings on the dial designate ounces -of pressure By using differentcalibrated lsprings Yfor Ythe'spring 45 the physician may 'Lobtain largeand therefore .more accurately 'determined readings Jeven though @thepatients vexertable :pressure "is "very small.

In rFigure "4 there Sis :illustrated :still vanother embodimentof l'the:present invention wherein instead of .pressure bellows, only a springisused. In this structure, as in 2 the #structure previously described,the size of the device is Jsuch lthat it may lbe 'readily igSr-'ip'pedhy "the hand v'of "a 'physician. The structure linclu'des a lcylindricalvcasing: internally threadedlat each end and closed at ie'achfendbyiclosiire plu'gs '15| and 52. A`A .contour gauge 53 fis'inoun'tedon the closure .plug 52, said :gauge having falscaletfand a pointer"antifa followeripointeri5'6 that reads the maximum lposition oftheipointer 55,`the.p0inter '55 being resetby azmanually'foperable knob28 the same .as lwasfheretofore described in connection with Figure 2.Ansaotuating .plunger 53 Vextends from ithe'gauge -fthroughtheplug l52,being slidable `therein. :A isprin'g "50 within lthe lcylinder 50 bearsat one end against the plug 52 and at its other end bears against alongitudinally movable head 83 that has threaded therein a threaded.shank 54 at the end of a rod 55 that is slidable through the plug 5i.The end of the shank Si! bears against the end of the actuating plunger58. The rod S5 has a knob I I at the end thereof which knob correspondsfunctionally with the knob I i previously described. When the cylinder59 is heid in one hand a pressure against the knob H forces the rod 95inwardly of the cylinder and thus forces the head B3 inwardly by anamount determined lby the pressure exerted and the stiffness of thecalibrated spring 60. The longitudinal movement of the actuating plunger58 is transmitted to the pointer 55 which thus moves across the scale 54and also moves the pointer 56 to a position corresponding to the maximumposition reached by the pointer 55. 1f it is desired to change thecalibration of the gauge 53 it is merely necessary to replace the springby another calibrated spring of greater or lesser stiffness. Also, ifdesired, an additional calibrated spring, corresponding to the spring45, may be added between the plug 5l and the knob Il.

A calibrated spring, such as the spring d5, may be added to thestructure of Figure 1 in a simple manner as, for instan-ce, byunsere-wing the knob H and then slipping the spring over the rod 8 andthe-n replacing the lniob.

While I have herein spoken essentially of an instrument wherein theactuation is obtained by pressure, it of course, obvious that theinstruments herein shown may be used to measure a pull instead or" apush. Also, ir" desired, the pressure of the fluid in the bellows ofFigures 1 and 3 may be transmitted. by means of a tube to a directreading or recording gauge at a point remote from the instrument itself.

In compliance with the requirements oi the patent statutes I have hereshown and described a preferred embodiment of my invention. It is,however, to be understood that the invention is not limited to theprecise construction here shown, the same being merely illustrative ofthe principles of the invention. What I consider new and desire tosecure by Letters Patent is:

l. A device for measuring muscle strength comprising a tubular casingadapted to be held in the hand, a closure hermetic-ally sealing one endof the casing, said closure including a pressure gauge having anindicator face or dial exposed on the outside of the casing, a secondclosure for the opposite end of the casing, an expansible bellows memberwithin the casing and comprising a sleeve extending from said secondclosure into the casing, said bellows together with the casing wall andthe first closure constituting a pressure chamber communicating withsaid gauge, a fluid within the chamber for communicating the chamberpressure to said gauge, a plunger siidable through sai-:i second closureand into the sleeve formed by the bellows and bearing on the end of thebellows remote from the second closure for actuating the bellows, andmeans on the portion of the plunger outside the casing for actuating thesame.

2. A device for measuring muscle strength comprising an open endedtubular casing, a closure overlying and closing one open end of thecasing, said closure including a pressure gauge telescoping into thecasing and having an indicator :face or dial extending across said openend of the casing and, exposed on the outside of the casing, a secondclosure for the opposite end of the casing, means forming a pressuredeveloping expansible bellows chamber within the casing and comprising acontractible and expansible bellows member forming a wall of saidchamber in the casing, said bellows pressure chamber communicating withsaid gauge, a liquid filling the chamber for communicating the chamberpressure to said a plunger slidable through said second closure andbearing on the contractible and expansible member for actuating thecollapsible and expansible member, and means on the portion of theplunger outside the casfo-r actuating the same.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,i8,582 Nelson Feb. 27, 1912 1,559,921 Treuheit Nov. 3, 19251,817,315 Knapp Aug. 4, 1931 1,892,988 Wahl Dec. 27, 1932 2,039,337Nolan May 5, 1936 2,450,188 Grai Sept. 28, 1948 FOREIGN PATENTS NumberCountry Date 565,314 France Nov. 6, 1923

